engleski

Cerebral organoids: in vitro model for brain development and neurodegeneration

Human, mammalian, brain development is a very complex process and starts shortly after gastrulation. Human in vitro models for brain development as well as pathological changes were published in last few years, eliminating the ethical concerns that accompany the study of aborted foetal material. One of the recent approaches is the development of induced pluripotent stem cell (iPSC) technology and different types of organoids, which can be applied to any species. In our previous work we developed iPSCs from an adult individual with constitutional mosaicism for Down Syndrome (DS) (1). From those iPSCs, cerebral organoids were grown and corticogenesis and Alzheimer-like pathology in vitro were studied (2). Mixed cerebral (2), as well as midbrain (unpublished) organoids were grown in vitro from the isogenic, trisomic and disomic iPSCs. Organoids were analysed histologically by IMARIS software. Foetal human brains were stained with the same combinations of antibodies and the data were compared. Anonymized post-mortem brain samples were obtained from the Brain Bank of the Croatian Institute for Brain Research (CIBR). Isogenic cerebral organoids expressed the markers of all six cortical layers (Reelin, FOXG1, SATB2, TBR1, Ctip2 and Brn2) after 100 days differentiation in vitro (DIV). At the early time point of DIV30 the majority of cells were Nestin, SOX2, PAX6 positive. At that time point neurogenesis had already started, so we observed TRBR2, DCX, MAP2 and TUBB3 positive cells in disomic and trisomic organoids. Following further neuronal differentiation of cerebral organoids we observed decreased number of neural stem cells and increased number of neuronal markers specific for all six layers. On the other hand, midbrain organoids expressed markers specific for midbrain. At the early time points midbrain organoids expressed neuronal stem cells markers, similar to cerebral organoids, but with organoid maturation we found midbrain specific cells such as NURR1 and OTX2 specific for the early stages, and later Dopamine β Hydroxylase, NET and TH. Finally, all those markers were compared with expression in foetal human brain from individuals with Down Syndrome as well as euploid controls age, sex and brain region matched. Our data showed that isogenic cerebral organoids grown from iPSCs are good tool for multidisciplinary studies. In our group we study corticogenesis, synaptogenesis, pathology and possible drug treatments.

Human iPSC, Trisomy 21, Brain Development

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